The invention relates to a process and portable devices for changing temperatures in accordance with the adsorption principle wherein operating agents are evaporated from a predetermined amount of operating agents being adsorbed in an adsorption agent by releasing the adsorption heat.
Processes and transportable devices for cooling and heat generation in accordance with the absorption principle are known. An easily evaporating operating agent is absorbed by a more difficult absorption agent. Useable cold is generated during the evaporation of the operating agent, while also useable absorption heat is released in the absorption agent during the absorption. Shut off devices within the steam chamber prevent an absorption outside of the operation. The cold or heat generation is initiated by opening the shut off devices. For reactivating the devices, the absorption agent is heated and the escaping operating agent is condensed. Devices in accordance with this process permit either the heating or cooling of goods, for example, foodstuffs or drinks.
All devices thereby depend on a heat exchange with the environment. For example, if an article should be heated with the released absorption heat, the evaporation heat for the operating agent must be simultaneously received from the environment. If, in the reversed situation, the goods should be cooled, then the absorption heat must be discharged to the environment. Very expensive heat exchangers are provided for this heat exchange which render the portable systems heavy, expensive and inert due to low heat transfer coefficients. Therefore, disposable devices which are suitable for a one time use become uneconomical. Adiabatic processes without heat exchange with the environment are not possible with the known pairs of absorption substances.
The requirements for the pairs of absorption substances are numerous. Only a few pair of substances have a sufficiently wide field of solution and the thermodynamic basic prerequisite for a sufficient temperature distance between the evaporation and the absorption. Furthermore, they should be easily regeneratable, non-corrosive, non-toxic and stable. Compatibility with the environment must be assured, in particular, with disposable devices. An accidental contact with foodstuff should not result in any damage. Portable devices should be lightweight in construction. Therefore, the container walls must be thinly constructed. Hence, high operating agent steam pressures are not suitable. The reaction kinetic must occur rather rapidly. Hitherto, no pair of substances could be mentioned which would meet these requirements.